I run into this more often than you would think.
I’ll be working with a controls engineer, or in a manufacturing facility in front of a PanelView Plus or FactoryTalk View SE SCADA system, when I notice the system seems to be running slow.
This sluggishness often has nothing to do with the type of network being used. I’ve seen it happen on RIO as often as I’ve seen it on Ethernet.
The reason for it is almost always caused by a default setting of every new project and display you create within View Studio: The “Maximum Tag Update Rate.”
However, it defaults to a sluggish 1 second update rate.
Now you may think that 1 second isn’t too bad. But when set at 1 second, I typically see a round trip response from “button push” to “on-screen indication” of nearly three seconds.
Why? Well, if you press the button just after the update occurs, you’ll have nearly a whole second go by until it’s read. And once it’s read and sent to the PLC, you’ll then have close to another second until the screen updates again to indicate its on.
Now in my time working with in-plant operators, I’ve come to the conclusion that they feel most comfortable with a response time of one second or less.
If the screen doesn't respond in a second or two, they'll often assume it didn't read their input and press the screen again.
To avoid this, and insure at least a 1 second update rate, I’ve found you’ll need to set each graphic display screen's “Maximum Tag Update Rate” to at lease .25 seconds.
However (if your system has the bandwidth) I would recommend a .1 second update rate as it provides for a very snappy system more in-line with today’s expectations.
Unsure if your EtherNet system can handle these update rates? Check out our previous article on using Rockwell’s Ethernet/IP Capacity tool which can help you quickly benchmark a system.
I hope you've found the above information about speeding up your FactoryTalk View Displays helpful.
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